<template>
  <div class="todo-footer" v-show="total">
    <label>
      <!-- <input type="checkbox" :checked="isAll" @change="checkAll" /> -->
      <input type="checkbox" v-model="isAll" />
    </label>
    <span>
      <!-- 利用filter过滤筛选 -->
      <!-- <span>已完成{{ todos.filter((todo) => todo.done).length }}</span> / 全部{{
        todos.length
      }} -->
      <span>已完成{{ doneTotal }}</span> / 全部{{ total }}
    </span>
    <button class="btn btn-danger" @click="clearAll">清除已完成任务</button>
  </div>
</template>

<script>
export default {
  name: 'List_select',
  props: ['todos'],
  //计算属性
  computed: {
    total() {
      return this.todos.length;
    },

    doneTotal() {
      //forEach筛选done
      /* let i = 0;
      this.todos.forEach((todo) => {
        if (todo.done) i++;
      }); */

      //educe筛选done
      return this.todos.reduce(
        (pre, current) => pre + (current.done ? 1 : 0),
        0
      );
    },

    isAll: {
      get() {
        return this.total === this.doneTotal && this.total > 0; //当已完成数等于全部数---checkall打钩
      },
      set(checked) {
        // this.checkAllTodo(checked); //但点击checkall触发事件checkAllTodo
        this.$emit('checkAllTodo', checked);
      },
    },
  },

  methods: {
    //e.target(点谁返回谁)返回的是触发事件的对象（元素）
    // checkAll(e) {
    //   this.checkAllTodo(e.target.checked);
    // },

    clearAll() {
      //   this.clearAllTodo();
      this.$emit('clearAllTodo');
    },
  },
};
</script>

<style scoped>
/*footer*/
.todo-footer {
  height: 40px;
  line-height: 40px;
  padding-left: 6px;
  margin-top: 5px;
}

.todo-footer label {
  display: inline-block;
  margin-right: 20px;
  cursor: pointer;
}

.todo-footer label input {
  position: relative;
  top: -1px;
  vertical-align: middle;
  margin-right: 5px;
}

.todo-footer button {
  float: right;
  margin-top: 5px;
}
</style>
